The entire point of PKI is that the public key is meant to be public. The impact on your security if a properly-created public key gets out is absolutely nil. I don't see any reason to hide them, save for an irrational belief that only comes from not knowing how the math works.
Noted upthread: there are some noncryptographic threats about revealing the identity of anonymous users, and conceivably giving people information about which devices to steal in order to impersonate that developer. (The second is mitigated a bit by stripping the comments, but is still conceivably a source of information.)
How is a public key revealing your identity? You can generate as many pair as you want. If you want your identity on github to be masked just generate a key specifically for github
This is all fine and well if you know that github exposes your keys. Which, at least wheb I added my keys, was not mentioned in a big, red button in the key dialog. Maybe I trusted GH too much by not creating a separate key pair for them. But information about me is being leaked without my knowledge, and that's wrong.
Yes, I for one didn't know that GitHub did this. If I had had a pseudonymous account that I trusted GitHub to protect, it would have exposed my identity because I wouldn't have realized it was important to make separate SSH keys.
Edit: Elsewhere commenters say GitHub wouldn't have allowed this for a different policy reason, so this problem couldn't actually come to pass.
The entire point of PKI is that the public key is meant to be public. The impact on your security if a properly-created public key gets out is absolutely nil. I don't see any reason to hide them, save for an irrational belief that only comes from not knowing how the math works.